Precision tubes and precision bellows with special dimensional accuracy

In our precision bellows manufacturing site, located in Poland, as a first step we make deep-drawn precision tubes. Mera Bellows is specialized in the production of very thin-walled tubing with closed ends. Using these thin-wall metal tubes, with special hydroforming techniques, we then manufacture precision bellows. For designing considerations, the application is of paramount importance. Is the bellows used as coupling for rotating shafts in drive technology, as metallic sealing or pressure sensor? What is the lifecycle requirement? Also, how long is the maximum compression and extension (stroke) that the metal bellows has to perform? Another focal aspect are pressure differentials: It is important to specify the pressure difference between the inside and outside of the bellows – and also the maximum working pressure that the precision bellows has to withstand. Furthermore, the spring rate (N/mm) has to be defined. It gives information about the amount of force that is needed to flex the bellows. Temperature extremes, surrounding media and, of course, geometric limitations have to be considered as well by the producer in order to finally supply a suitable and sustainable component.

As part of our zero-failure philosophy, every production process is monitored and statistically analyzed. The 100% final control, including leak testing for all precision bellows, ensures that only excellent products are delivered to customers. Additionally, Mera Bellows has the possibility to apply spring rate testing, cycle testing and other measurements in order to guarantee products of the highest precision.

Precision bellows of Bronze as thermal actuator for thermostatic valves

It is crucial to select the right material for your precision bellows

Different metals and alloys are suitable for the production of our precision tubes, including different kinds of stainless steel, brass, bronze, and alloys of nickel-copper (Monel400) or beryllium-copper. Offering seamless constructions, we can achieve small tolerances in diameter and wall thickness. That helps us to guarantee a stable performance for all our precision bellows. Based on their small spring rates, Mera Bellows precision bellows made of non-ferrous metals (especially tombac and bronze) are especially suitable for measuring, controlling and regulating applications. Precision bellows with bottom (one closed end) are used to convert pressure into movement. In thermostatic heads, for instance, our closed-ended bronze bellows are used millionfold for heating systems all around the world. The thermostat bellows behave like a spring. They are filled with alcohol and actuate the mechanical system. If the temperature rises, the precision bellows expands in an axial direction. The thermostatic valve flow is reduced for an exact temperature regulation. If room temperature decreases, the bellows shortens – and consequently, the regulator valve opens and heating capacity increases again.

Our stainless steel precision tubes are requested to withstand extreme environments and high working pressures. They can be implemented for the distribution of very hot liquids. The precision metal bellows, manufactured in one of our standard stainless steels are often implemented as flexible maintenance-free hermetic sealing of valve spindles. In order to guarantee the required amount of load cycles while surrounded by critical media, a resistant material is needed. Other projects require high electric conductivity or extra flexible constructions. For all purposes, Mera Bellows manufactures customized precision tubes and precision bellows according to your exact specifications.

Stainless steel precision bellows for pressure switch applications

Other applications of Mera Bellows precision tubes and precision bellows

Thin wall precision cups and tubes are used in industries such as automotive, aviation, or in medical engineering, e.g. as connection elements. Our smallest seamless precision bellows start at 4.2mm ID and less than 0.1 mm of wall-thickness if needed. Along with the many other applications that were mentioned before, our hydroformed precision bellows are also implemented worldwide as core elements of pressure switches or accumulators. In oxygen masks, metal bellows are used to control the valve opening as the precision bellows expand and contract with altitude. More examples include vacuum applications such as vacuum valves or vacuum interrupters. As core elements in these circuit breakers and other utilizations in vacuum chambers, mostly stainless steel precision bellows are implemented. Besides the precondition to meet very high tolerance specifications, for safe use, a superior surface quality is needed, particle- and stain-free.